Omron NX-ID User Manual page 123

The voltages and currents related to the conditions for PNP type sensors are shown in the figure
below.
Two-wire sensor
V : Power supply voltage
CC
V : Sensor's output residual voltage
R
V : OFF voltage of DC Input Unit
OFF
I : Sensor leakage current
leak
R: Bleeder resistor
I : OFF current of DC Input Unit
OFF
R : Input resistor of DC Input Unit
IN
(d) Precautions on sensor inrush current
An incorrect input may occur due to sensor inrush current if a sensor is turned ON after the DC Input
Unit has started up to the point where inputs are possible.
Determine the time required for sensor operation to stabilize after the sensor is turned ON and take
appropriate measures, such as inserting an ON delay into the user program after turning ON the
sensor.
A programming example is shown below.
The sensor's power supply voltage is used as the input bit to Sensor_power.
A 100-ms timer delay (the time required for an OMRON Proximity Sensor to stabilize) is created in
the user program.
After the timer changes to TRUE, input bit X causes the output Output to change to TRUE after the
input of the sensor changes to TRUE.
Sensor_power
NX-series Digital I/O Unit User's Manual (W521)
V V
R CC
I
I
leak OFF
V
R
OFF
TON
T#100ms
IOV
Communications Coupler Unit or
Additional I/O Power Supply Unit
IOG
IOV
DC Input Unit
IN
R
IN
IOG
X
4 Installation and Wiring
Output
4
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